Induction motor



C. 30, 1951 W T SE1-r2 2,573,283

INDUCTION MOTOR Filed May 19, 1949 3 Sheets-Sheet l Oct. 30, .1951 W, T SEH-Z 2,573,283

INDUCTION MOTOR Filed May 19, 1949 3 Sheets-Sheet 2 INI/ENTOR. 'fl/QL 75%? F/TZ Filed May 19, 1949 W. T. SEITZ INDUCTION MOTOR 5 Sheets-Sheet I5 figg f @40 Mn o El# H/ 52 /g f/ U INVENTOR. WAM/*EQ 7.' $5/ rz Patented Oct. 30, 1951 UNITED STATES PATENT OFFICE .INDUCTION MOTOR `Wa1ter T. Seitz, Etna, Pa.

Application May 19, 1949, Serial No. 94,181

4 Claims. l

This invention relates generally to induction motors, and more particularly to induction motor-s having a radial armature with dual stators having multiple windings and disposed on opposite sides of the lrotor and having relative arcuate movement to .each `other for varying `the speed and the direction of rotation of the armature.

.Induction motors .having radial armatures and :flat lstat-ors are disclosed in the art and one is known on Ythe market as an axial air gap motor. The art also teaches the use of a long prepunched .iron strip spirally wound Yto form the core of the rotor or stator of a .radial type induction motor. When the core is completely wound, the prepunched openings form continuous radial .slots for receiving the windings and bars of the stator :and armature, respectively. The rotor slots for receiving bars .may be skewed lor curved as they progress outwardly. The comparatively large diameter of the rotor relative to .-that of the ordinary induction motor of the same capacity provides a materially greater flywheel eifect and since the rotor is not encircled by the stator, it may operate at a materially lower temperature or function as a greater capacity motor when operated at a temperature ordinarily experienced in a Acoaxially concentric induction motor.

The object and advantage of the present disclosure vis the provision of -a radial type induction motor having multiple windings in opposed stators that permit the motor to be connected `and operated as -a single or multiple phase motor. One or both stators may be mounted for arcuate Amovement relative to each other for the purpose of reversing the rotation of the motor and at the same time providing iniinite variable speeds in operating opposite directions.

By employing a plurality of windings on each of two opposed stators, selected windings of each stator may be coupled to complete a secondary circuit therebetween for the vpurpose of operating the motor from a single phase alternating current .Supply with the advantages of reversal in rotation .and variable speed by lmoving one stator arcuate vand axially relative to the other.

.Single windings in each of the spaced stators .on opposite sides of the rotor may be connected through inductive and capacitive reactances to operate the motor on single phase, the direction .of rotation and speed of which may be varied by shifting the -stators relative to each other. By using multiple windings in each stator, selected windings Vmay be inductively energized and the secondary -coils may be connected through a selected reactance to operate on single phase.-

(Cl. S18- 243) pose of exemplication, without limiting the invention or claims thereto, certain practical embodiments of the invention wherein:

Fig. 1 is a sectional view of the multistator .motor comprising this invention;

motor comprising this invention connected for single phase and employing a winding in each vstator and a reactance;

Fig. 5 is a circuit diagram of a single phase dual stator motor having a winding in each stator with a capacitive reactance in series with one winding and an inductive reactance in series with another winding;

Fig. 6 is a circuit diagram of a single phase dual stator motor employing two windings in series in the rst stator and two windings in multiple in the second stator and a reactance connected in series with the rst windings;

Fig. 7 is a circuit diagram of a single phase motor having an inductive reactance connected in series with one of two windings in the rst stator that are connected in multiple and a capacitive reactance connected in series with the multiple connected windings of the second stator;

Fig. 8 is a circuit diagram of an inductively coupled single phase motor having two windings of the first stator connected in series and across the secondary winding of the second stator;

Fig. 9 is a circuit diagram of an inductively coupled single phase motor having one winding Vof the rst stator connected in multiple with a.

secondary winding in the second stator;

Fig. 10 is a circuit diagram of an inductively l.coupled single phase motor similar to that shown .coupled single phase motor with a secondary winding of the nrst stator connected in multiple with a corresponding secondary winding of the second stator and a reactance placed in series with each pair of windings and with the primary windings connected across the line;

Fig. l2 is a circuit diagram of an inductively coupled single phase motor similar to Fig. 1l with the leads of one induced winding reversed;

Fig. 13 is a circuit diagram employing a dual stator radial motor connected as a two phase motor, employing a winding in each of the two stators;

Fig. 14 is a circuit diagram similar to Fig. 13 but also includes a parallel connection between the secondaries of each stator;

Fig. l is a circuit diagram of a three phase motor employing a winding in each stator;

Fig. 16 is a circuit diagram of a dual stator radial type motor with each stator having three windings formed and connected as a three phase motor with the connections being made in closed delta;

Fig. 17 is similar to Fig. 16 with the connection being made in star; and

Fig. 18 is a circuit diagram of a dual stator radial motor having selected primary and secondary inductively connected directly and with the primary and secondary circuits inductively connected through a transformer.

Referring to Figs. 1 to 3 of the drawings, the dual stator radial induction motor shown is enclosed in the open ended cylindrical casing I .engaging and secured to the end bells 2 and 3 which may be cast with feet l and 5 for supporting the same. Each end bell is arranged to carry frictionless bearings S and I that are axially aligned to support the shaft 8 and rotatably support the rotor 9, fixed thereto. The shaft extends through the stators IB and I I which have central -openings and are carried by the spiders I2 and I3 that are in turn clamped between the shoulders on the cylinder I and the end bells 2 and 3. The

ystator I2 is provided with a series of annularly spaced threaded openings for receiving the bolts I4 that extend through arcuate slots I5 in the spider I2 and carrythe revolvable sleeves I6. The arcuate slots I5 in the spider permit the stator Ii) to be adjusted through an arc greater than 180 electrical phase relation to permit the windings in the stator I2 to be shifted from a full .speed in phase position with respect to the windings of the stator I I, through an opposed phase relation that causes the rotor to stop, to an opposite in phase relation causing the rotor to rotate at full speed in the opposite direction. For this purpose a gear segment I1 is attached to the perimeter of the stator Il! and is engaged by the worm gear I on the shaft I9 that is carried by bearings on the spider I2 and extends out through'the housing and is provided with the ,hand wheel 2l! for adjusting the angular position of the stator I0. Any suitable mechanical or electromechanical means, such as indicated by the motor 2 I may be employed to selectively position the stator I0 by a manual control of the motor 2l or by remote control to vary the speed and reverse the direction of rotation of this induction motor.

The stator II may be secured to its spider I3 Yby the bolts I4 extending through the holes 23 by simultaneously rotating both stators in opposite directions.

The stators IIJ and II are preferably made by winding a long prepunched strip of transformer Steel on a ring such as indicated at 24, which may be formed by welding the end of the strip to itself after completing the first complete turn. The consecutive punched openings in the single or continuous strip must be spaced at a uniformly increasing distance in order to match one another as the diameter of the stator increases in order that the completed iron core is provided with well formed radial slots to receive the coils. If it is desired to have the slots skew from the radial, the spacing between the punched openings may be varied so that they do not quite mate for each turn of the steel strip, but the prepunched openings should be somewhat larger to accommodate the coils. The last turn making up the laminated stator may be welded on itself. The back face of the stator cores may belightly welded in a crisscross fashion in orderv to insure the permanency of this spirally wound transformer steel.

The punched openings in the stator Iii have been made to produce twentyfour radial slots and the punched openings of stator I I have been made to produce thirty-two slots, which was found to work satisfactory in the same motor wherein the copper spider making up the squirrel `cage type rotor had only twenty-one radial bars.

I ing as to power and speed.

The armature or rotor may be made up with prepunched transformer steel shown at 24 iii Fig. 3 to form slots 0n both sides thereof for use with two sets of radial copper bars 25 and 26 connected at their ends with the coaXially concentric copper rings 2`I and 28 forming the inner and outer rings of the armature. These two sets of rotor bars may be aligned with one another or oiset for the purpose of obtaining selecte't operating characteristics of the induction motor. However, the continuous strip of steel is spirally wound in the same manner as that of the stators and the slots are slightly skewed. This structure divides the motor in two parts with respect to the circulatory fluid system and the armature functions as an impeller in a centrifugal pump to draw air through the end bells and the open center of stators which is then forced radi-t ally past the front face of the stators and out through openings in the casing as shown by the arrows in Fig. l.

The two stators shown in Fig. 2 have the coil windings indicated thereon and each provides for four poles and the same number of slots. Each pole has two windings or coils that are entirely independent of one another, but may be connected in multiple which would amount to a single coil of larger size wire. If they are connected in series they may be considered as a single coil of more turns. They are also employed independently as primary and secondary windings in some hookups to be described hereinafter. For the purpose of this disclosure 3B. and 3I represent the rst set of comparable windings on the stators II and Ill, respectively, and 32 and 33 represent the second set of comparable windings on these stators making four windings` in all. Each winding on each stator is shown asapplied in four poles of one stator. The slots of' permit the coils `to Abe laid `therein with the rst few complete turns being in adjacent slots, vthe next few turns in the next adjacent slots .and so on Aas indicated in Fig. 2, the last few turns being the longest since they form the boundary of the pole. The two coils for each pole may `be wound in the slots simultaneously or one may be laid von 'top of the other, whichever is most convenient. Sometimes, only one winding `-is required on one of the stators in some circuits., but in each instance the size of wire, number of turns and the proper amount .of iron and vthe size of the slots should be, of course, calculated for each design and size of motor. It is also obvious that motors of .different sizes should have Va different number' of poles. In Fig. 2, the leads from coils .of adjacent poles are connected to reverse the direction of current flow for both windings. The current now in the winding of one pole coil should yalways be in the same direction as the current flow through the coil of the other winding of the same pole.

VThe rotor 9, shown between the two stators of Fig. 2, is of .the squirrel cage type having the nonmagnetic hub secured to the lshaft .S and .provided with a series of radial :bars 3.5 extending like spokes .of a wheel and preferably :inserted 'in and joined to the coaxially concentric rings forming the hub 35 and the rim 31. These parts are preferably made of copper and are suiciently strong to withstand the centrifugal force. This rotor has .an odd number of spokes or bars, such .as twenty-one., and they are wound with iron wire as .shown at 3'3. This continuous iron wire may be wound on the rspokes before the rim 3'! is placed thereon. The iron wire 38 is started adjacent the hub 35 and woven in and out of adjacent spokes. Since there are only twenty-one bars or spokes, this pancake rotor has the same number of wire turns on one side of each bar as it has on the opposite side. It is of course desirable to place as much iron wire on this rotor as possible, and in the structure shown there is approximately twenty-four turns of iron wire. "The other rotor .shown in Fig. 3 has .materially more viron and is therefore considered preferable. .It .is also .heavier and provides a greater flywheel effect. It .may not be desirable to make the rotor too heavy if it is to be reversed quickly and frequently, so too Amuch iron `may bey undesirable for rapidly reversing motors, but for unidirectional motors the iron strip of the rotor in Fig. 3 may be made wide to intentionally vincrease the ywheel eiiect.

The circuit diagrams .showing the diiierent ways in which this radial motor can be connected for operation is shown in Figs. 4 to 15, inclusive. The windings indicated on each side of the rotor 9 represent the windings of the opposed stators, one or both of which may be rotated relative to each other for the purpose of placing them in phase to operate the motor at full speed in one direction, to 180 electrical phase relation to operate the motor in the opposite direction at full speed and at the mid point of these positions the motor will stop. Although the windings are fully energized, they oppose one another and lock the rotor from turning. Thus, innite speed adjustment may be obtained by arcuately moving one or both stators.

In the circuit of Fig. 4 one winding 32 is indicated for stator Il] and one winding 3l is indicated for stator Il. Of course these windings may be a heavy single wire winding or two lighter wire windings in multiple or in series as `thecircuit is merely illustrative diagrammatically for single phase. The winding 32 is connected in series with a reactance or impedance 4i) to shift the phase vbetween the two windings and they both receive energy directly from the alternating current source such as single phase 115 v. 60 cycle current. With two coils in multiple in each stator and a capacitive reactance at G0, the speed of the rotor was found to be approximately 1400 R. P. M. If only one coil in each stator is employed with a capacitive reactance dil, the speed was of course proportionately reduced to 900 P. M. With two coils in multiple in stator H and one coil in stator I8, and a capacitive reactance 40, the speed was further proportionately reduced to 600 R. P. M. and with an inductive reactance at 40, it rotates at only R. P. M. Thus, the ampere turns per winding and the reactance 40 may be selected to provide a single phase rotor of the desired characteristics and the speed can be varied by increments from the maximum to zero and reversed in rotation by shifting one or both stators.

In the circuit of Fig. 5, a capacitive reactance 4l is in series with one winding and an inductive reactance 42 is in series with the other winding and both winding circuits are connected in parallel across the alternating current Vsingle phase source. The circuits of Figs. 4 and 5 are in effect a 'split phase induction motor circuits yet the windings are in opposed stators that have relative arcuate movement to vary the speed and reverse the direction of rotation without changing the hookup.

The circuit of Fig. 6 carries the dual stator motor connections one step further in that the two windings 32 and 34 of stator ID are connected in series while the windings 3l 'and 33 of stator Il are connected in multiple with the reactance 40 in series with the windings 32 and 34. The comparative speed of this circuit is about 600 R. P. M. with a capacitive reactance 40 on v. 60 cycles.

In the circuit of Fig. 7, the inductive reactance 42 is placed in series with winding 34 and the capacitive inductance M is placed in series with both windings of stator` I0. This hookup operates the motor at a top comparative speed or about 1200 R. P. M.

In the circuits of Figs. 4 to '7, one or both of the windings in each stator are directly supplied with current from the alternating current source. However, in Figs. 8 to 12, some of the windings are inductively energized.

As shown in Fig. 8, the alternating current source is supplied to winding 3-3 of stator il which provides a primary winding inductively coupled to the winding 3l of the same stator, which in turn is electrically connected to the windings 32 and 34 in series with one another. This inductive connection eliminates the necessity of any reactance and the top comparative speed of the motor is 300 R. P. M.

The inductive coupling shown in Fig. 9 is similar to that of Fig. 8, but employs only winding 32 of stator l0 in the secondary circuit, and when the switch 43 is closed to short the reactance 40, the motor operates at about 600 R. P. M. With the reactance in the circuit, the speed is reduced slightly indicating proper vphase relation of the inductively coupled windings which do not require further phase shifting. The speed and reversal in direction of rotation may both be changed by moving the stators relative to each other in each of these instances.

By placing the windings 32 and 34 in multiple as shown in Fig. 10, the speed is increased to 800 R. P. M. Thus, Figs. 8, 9 and 10 indicate that an increased ampere turns in the stator III which increases the comparative speed accordingly when such windings are inductively energized.

In Figs. 11 and 12, the circuits are split phase and inductively coupled. With a capacitive reactance at 40 in the primary circuit and an inductive reactance 44 in the secondary circuit, the hookup of Fig. 11 operates at approximately 1,000 R. P. M. and in Fig. 12 about 400 R. P. ML,

the difference being brought about in reversing the connection of the secondary winding 3l of stator I I as shown in Fig. 12. However, the same effect in reduction of speed may be produced in Fig. 11 by making the reactance 40 inductive and the reactance 44 capacitive which results in a comparative speed of approximately 400 R. P. M.

This dual stator radial motor is ideal for operation as a two phase motor as illustrated in Fig. 13, wherein the windings of each stator are connected to their separate phases. An inductively coupled hookup for two phase is shown in Fig. 14 wherein it is preferable to reverse the leads of one of the secondary windings which in the case shown is winding 3 I.

A star connection for three phase is illustrated in Fig. 15 wherein one end of the windings of one stator is connected to one end of the windings of the other stator to lprovide one phase line and the other ends of said windings for each of the other two lines.

The diagrammatic view of Figs. 16 and 17 require the stators I and II to be wound with three coils each, 45, 46 and 41 in stator I0 and 48, 49 and 50 in stator I I. These coils are wound in the stators in the manner of any three phase induction motor and in Fig. 16 are connected in delta, while in Fig. 17 they are connected in star with the windings of one stator connected in multiple with the windings of the other stator. By turning one or both stators from an in-phase position to an out-of-phase position, the speed of the induction motor may be regulated to la very fine degree from full speed to stop.

In the structure of Fig. 18, the single phase windings are connected as illustrated in Fig. 11 with the reactances 40 and 44 omitted and an inductively coupled transformer reactance I, with its windings 52 and 53, is employed in its stead. The winding 52 being in series with the windings 33 and 34 of the primary circuit. The winding 53 is in series with the windings 3I`and 32 of the secondary circuit. Without this inductive reactance the motor of this circuit is not self-starting.

Ll l) While, for clarity of explanation, certain prferred embodiments of this invention have been shown and described, it is to be understood that this invention is capable of many modifications, and changes in the construction and arrangement may be made therein and certain parts may be employed without conjoint use of other parts and without departing from the spirit and scope of this invention.

I claim:

l. A rotary induction motor comprising a housing, a rotor mounted for rotation in said housing, two stators mounted in the housing with one positioned, on each side of said rotor, one of said stators movable about the axis of said rotor, a primary motor winding in the first stator, a secondary winding in the first stator inductively coupled with said primary motor winding, a winding in said second stator, a reactance, and a circuit connecting said reactance and said secondary winding and the winding in the second stator in a closed circuit.

2. The structure of claim 1 which also includes a reactance in the circuit of the primary winding effective for shifting the primary and secondary currents farther apart than that produced by the reactance in the secondary winding circuit.

3. The structure of claim 1 which also includes a primary motor winding in said second stator inductively coupled with the winding in said second stator.

4. The structure of claim 1 which also includes a reactance in the circuit of the primary winding that is inductively coupled independently with the reactance in the circuit of the secondary winding.

WALTER T. SEITZ.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 504,914 Eldredge Sept. 12, 1893 514,907 Bush Feb. 20, 1894 727,662 Meuschel May 12, 1903 1,237,681 Neuland Aug. 21, 1917 1,419,749 Murphy June 13, 1922 1,605,796 Tanzler Nov. 2, 1926 1,829,686 Swendsen Oct. 27, 1931 1,893,112 Swendsen Jan. 3, 1933 1,977,950 Morhard Oct. 23, 1934 1,998,142 Meyertons Apr, 16, 1935 2,324,728 Schiff July 20, 1943 2,479,589 Parker Aug. 23, 1949 

